The three dimensional position coordinates of a mobile object can be determined in a variety of ways. In recent years, the global positioning satellite (GPS) receivers and the receivers that use the alternative satellite systems, like GLONASS system, came of age and began to proliferate widely. An autonomous navigational system that includes a satellite receiver and a navigational computer can achieve the 10-meter level of accuracy in the position determination of a mobile object.
The differential navigation systems that utilize the differential corrections in addition to the satellite signals can determine the positional information with the meter-range accuracy. The real-time kinematic (RTK) GPS systems that are capable of utilizing in real time not only code but also carrier information transmitted from satellites can achieve the centimeter level of accuracy in the position determination of a mobile object.
Recently, the alternative laser based navigational systems were developed by a number of companies. For instance, the IBEO Lasertechnik, based in Hamburg, Germany, developed a Ladar 2D navigational sensor system that is capable of navigating a mobile unit equipped with a scanning and rotating laser beam and a navigational computer. The laser beam is reflected by a number of laser reflectors placed in positions with known coordinates. The Ladar 2D navigational system determines the ranges between the mobile unit and the laser reflectors that reflect the laser beam illuminating them. By solving the simple geometric equations, the navigational computer can determine the mobile unit 2D position coordinates and navigate the mobile unit in real time with accuracy up to 2 cm.
However, the laser reflectors have to be placed in the locations with known coordinates for the laser positioning system to become operational. This requires that the survey of the laser reflectors be performed independently from the navigation of the mobile unit.
What is needed is a satellite navigational system augmented by a laser positioning system that is capable of surveying the laser reflectors and navigation of the mobile unit at the same time.